#1. Check a salvage yard. Since many will have crushed what's left of their stock of anything older than 10-12 years, you may have to try a specialty yard or a place like
http://www.moderndaymuscle.com/home or
http://www.hawksthirdgenparts.com/index.asp or somewhere similar.
#2. If the car is an original 1984 Camaro, it isn't going to have a 350. It would have had either the 151 four-cylinder, the 171 V-6, or a 305 V-8 (which will look identical to a 350). 350s in ThirdGens did not appear until 1987 from the factory. Unless someone has swapped engines, you might want to check the casting numbers on the rear ledge of the block to verify that, but if it's stock, it's not a 350.